Hand force feedback and sensing system

ABSTRACT

The present invention relates to a force feedback and sensing system for a hand in which an actuator system and sensing system is coupled to a palm base attached to the hand or a glove. The actuator system includes double acting actuators which provide force feedback against digits of the hand to simulate a real experience a user would have if directly manipulating a real object. The actuators are rotatably mounted to the palm base through a two degrees of freedom rotation joint.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a force feedback and sensing system forthe hand for providing an interface to an interactive system.

2. Description of the Related Art

Force feedback human interface devices are used to track a user's manualgestures and provide means of presenting physical sensations back to theuser. A force feedback device typically includes sensors for tracking auser's motions and actuators for producing physical forces.

Conventional systems have used the human hand to control bothnon-dextrous and dextrous slave devices. U.S. Pat. No. 5,004,391 ('391)issued to one of the inventors of the present disclosure describes acompact, hand-held unit that fits within the space defined by the user'spalm and fingers and functions as a position controller for a robothaving a slave hand. A finger position sensor including a linear,variable differential transformer provides an output signal that isproportional to the distance between the user's fingers. A forcefeedback system, including a pneumatic micro-actuator, senses the forcesexerted by the end effectors of the robot hand and causes acorresponding force to be exerted on the user's fingers. The foregoinginvention was intended primarily for use between the thumb and middlefinger of the operator's hand. As such, it limited the ability toprovide force feedback between any other fingers of the hand and alsorequired the usage of a special sensor system using a lineardifferential transformer between the two manipulating digits.

U.S. Pat. No. 5,354,162 issued to one of the inventors of the presentdisclosure describes an improvement over the '391 patent in which asensor glove is combined with a force feedback system. An actuatorsystem provides force feedback to a master support. A first, second,third and fourth digit supports are connectable by a finger mount to thethumb, index, middle, and ring digits, respectively. First, second,third and fourth actuators comprising pneumatic cylinders extend betweenthe first, second, third and fourth finger mounts and an “L” shaped palmsupport mountable on the palm of the glove. Sensors are mounted to thepneumatic cylinders to provide electrical signals on the positioning ofthe fingers. The signals are forwarded by a stand alone electronicinterface to a host computer. The host computer computes the positioningof the finger and provides feedback to the first, second, third andfourth actuators.

U.S. Pat. No. 6,028,593 describes a method and apparatus for providingforce feedback to a user operating a human/computer interface device andinteracting with a computer generated simulation. In one aspect, acomputer-implemented method simulates the interaction of simulatedobjects displayed to a user who controls one of the simulated objects bymanipulating a physical object of an interface device. The position ofthe simulated object, as provided within the simulation and asdisplayed, is mapped directly to the physical position of the userobject. The apparatus provides force feedback to the user which impartsa physical sensation corresponding to the interaction of the simulatedobjects.

Sensorial modalities have been used to increase simulation realismduring virtual object manipulation. Haptic gloves have been used ashaptic interfaces. Examples of haptic gloves have been described as the“Rutgers Master” in Gomez, et al., “Integration of the Rutgers Master IIin a Virtual Reality Simulation,” IEEE Virtual Reality AnnualInternational Symposium, pp. 198–202, (1995), as the “LRP Glove” in M.Bouzit, “Design, Implementation and Testing of a Data Glove with ForceFeedback for Virtual and Real Objects Telemanipulation,” Ph.D. Thesis,Paris, France, (1996), as the “CyberGrasp” in Turner, et al.,“Preliminary Tests of an Arm-Grounded Haptic Feedback Device inTelemanipulation,” Winter Annual Meeting of ASME'98, TX, DSC-Vol. 64,pp. 145–149, Nov. 15–21, Dallas, (1998). Force feedback bandwidth forthese devices is in the range of 10–50 Hz. The gloves have one or moreforce degrees of freedom (DOF) per finger with forces grounded in thepalm or on the back of the hand. A virtual hand maps the user's hand toa virtual environment.

It is desirable to provide an improved hand force feedback and sensingsystem that is lightweight and yet powerful. It is also desirable tohave a system that adapts to various hand sizes.

SUMMARY OF THE INVENTION

The present invention relates to a force feedback and sensing system fora hand in which an actuator system and sensing system is coupled to apalm base attached to the hand or a glove. The actuator system includesdouble acting actuators which provide force feedback against digits ofthe hand to simulate a real experience a user would have if directlymanipulating a real object. The actuators are mounted to the palm basethrough a two-degrees-of-freedom rotation joint. Preferably, the mountto the palm base includes a miniature bearing for reducing friction.

The system is compact and lightweight to prevent tiring of a user's handduring use. The shape of the palm base provides complete flexion of themetacarpal phalanx and is comfortable in a user's hand. Air tubing tothe actuator is preferably coupled directly or integrated with the palmbase to allow for full range of motion of the actuators.

Each actuator includes a piston moveable in a cylinder. A piston rod ismounted to the piston. The piston rod is extended and compressed withinthe cylinder. A self-locking fingertip mount can be used to attach theactuators to the bottom surface of a fingertip. The fingertip mount ismounted on the piston rod through a rotary joint.

The sensing system can comprise one or more of a linear sensor, anabduction angular sensor, a flexion angular sensor and a force sensor.The linear sensor can include a reflective infrared sensor which isactivated by receipt of transmitted infrared waves which are reflectedfrom a mirror attached to a bottom surface of the piston. The abductionangular sensor and flexion angular sensor can measure respective motionsbased on measurement of a magnetic field on two perpendicular axes. Theforce sensor can include a strain gauge for measurement of deformationof the palm base due to pressure applied by the fingertips.

The invention is described in more detail by reference to the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front perspective view of a hand force feedback and sensingsystem in accordance with the teachings of the present invention.

FIG. 1B is a perspective view of an embodiment of the system in which ahand mount attaches the palm base to the hand.

FIG. 1C is a perspective view of the hand mount from the bottom and sideof FIG. 1B.

FIG. 1D is a perspective view of the rear of the hand including theattachment of the hand mount shown in FIG. 1B and FIG. 1C and attachmentof a wrist position sensor to the hand mount.

FIG. 2A is a cross sectional view of an actuator used in the system.

FIG. 2B is an interior view of the actuator showing air flow directionduring compression and extension.

FIG. 3A is a schematic diagram of a piston rod of the actuator in anextended position.

FIG. 3B is a sectional view of a piston of the actuator connected to thepiston rod within an inner cylinder of the actuator.

FIG. 4A is a perspective view of attachment of cylinders of the actuatorto a palm base.

FIG. 4B is a schematic diagram of rotation of one of the cylinders on aflexion axis and an abduction axis.

FIG. 4C is a sectional diagram of a joint for mounting the actuator forproviding rotation on a flexion axis.

FIG. 4D is a sectional diagram of a joint for mounting the actuator forproviding rotation on an abduction axis.

FIG. 5A is a perspective view of a palm base including integrated airtubing connected to the cylinder of the actuator.

FIG. 5B is a top elevational view of the palm base.

FIG. 5C is an end view of the palm base taken from the right of FIG. 5B.

FIG. 6A is a schematic diagram of the actuator in a compressed positionof a digit of the hand.

FIG. 6B is a schematic diagram of the actuator in an extended positionof a digit of the hand.

FIG. 7A is a side elevational view of a fingertip mount connected to afingertip.

FIG. 7B is a perspective view of the fingertip mount.

FIG. 8A is a sectional view of a linear sensor used in the system.

FIG. 8B is a schematic diagram of a portion of a cover for a cylinderused with the linear sensor shown in FIG. 8A.

FIG. 9A is a sectional view of an angular sensor used in the system formeasuring an abduction angle of rotation.

FIG. 9B is a sectional view of an angular sensor used in the system formeasuring a flexion angle of rotation.

FIG. 9C is a perspective view of the angular sensors shown in FIGS. 9Aand 9B.

FIG. 10 is a schematic diagram of a force sensor used in the system.

FIG. 11 is a schematic diagram of an interface for use with the actuatorof the present invention.

DETAILED DESCRIPTION

Reference will now be made in greater detail to a preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings. Wherever possible, the same reference numerals will be usedthroughout the drawings and the description to refer to the same or likeparts.

FIG. 1A is a front perspective view of hand force feedback and sensingsystem 10 in accordance with the teachings of the present invention.System 10 includes actuator system 20 and sensing system 80 coupled bypalm base 50 to glove 12. Hand 11 is received in glove 12. Hand 11 hasthumb digit 13, index finger digit 14, middle finger digit 15, ringfinger digit 16 and little finger digit 17 each connected to palmportion 18. Preferably, actuator system 20, sensing system 80 and palmbase 50 are lightweight. For example, system 10 can weigh less thanabout 100 g.

Actuator system 20 comprises actuators 22 a, 22 b, 22 c and 22 d whichrespectfully provide force feedback against thumb digit 13, index fingerdigit 14, middle finger digit 15 and ring finger digit 16. Accordingly,actuator 22 a–22 d aid in opening or closing of digits 13–16. The forcefeedback is simulative of the real experience a user would have ifdirectly manipulating a real object. It has been found that fouractuators are sufficient to provide realistic response. It will beappreciated that actuator system 20 can be expanded to also include anactuator for providing force feedback against little finger digit 17.Glove 12, hand 11 and system 10 can have different sizes, i.e. “small”,“medium” and “large”.

In an alternate embodiment shown in FIGS. 1B–1D, palm base 50 isattached directly to hand 11 with hand mount 300. FIG. 1B illustratesactuator 22 b attached to palm base 50. It will be appreciated thatactuators 22 a, 22 c and 22 d can be also attached to palm base 50. Handmount base 302 is attached with a plurality of side mounts 304 to palmbase 50. For example, side mounts 304 can be formed of flexible beams.End 305 of side mounts 304 include aperture 306. Aperture 306 isreceived over post 308 attached to palm base 50. End 309 of side mounts304 is received in self-locking head 310. During use, hand 11 isreceived between bottom surface 311 of palm base 50 and top surface 312of hand mount base 302 and hand 11 is coupled by side mounts 304 to palmbase 50. Hand mount base 302 includes apertures 312 as shown in FIGS. 1Band 1C. Attachments 313 to wrist position sensor 314 is received inapertures 312. Wrist position sensor 314 can be a six degree of freedomposition sensor, for example as manufactured by Polhemus Inc. as “FastTrack”.

Each of actuators 22 a–22 d comprise moveable piston 23 which moveswithin cylinder body 24, as shown in FIG. 2A. In a preferred embodiment,cylinder body 24 is formed of outer cylinder 25 and inner cylinder 26which are seated on bottom cylinder cap 27. Outer cylinder 25 ispreferably formed of a metal, such as stainless steel, for supportingradial force or torques on cylinder body 24. Preferably, inner cylinder26 is formed of resistive glass, such as Pyrex, for supporting airpressure.

Gasket 28 a seals inner cylinder 26 to outer cylinder 25 and bottomcylinder cap 27. Gasket 28 b seals top portion 36 of inner cylinder 26to outer cylinder 25. Aperture 29 a is formed through gasket 28 a andaperture 29 b is formed in gasket 28 b. Air inlet 30 is positionedthrough bottom portion 32 of outer cylinder 25, as shown in FIG. 2B. Airinlet 31 is positioned through bottom cylinder cap 27. Air 33 from airinlet 30 received through aperture 29 a in gasket 28 a circulatesupwardly in the direction of arrow A₁, between outside 34 of innercylinder 26 and inside 35 of outer cylinder 25 through aperture 29 b ingasket 28 b to top portion 36 of inner cylinder 26. Air 33 enters fromtop portion 36 of inner cylinder 26 and pushes downwardly in thedirection of arrow A₂ thereby compressing piston 23 within innercylinder 26. Air 37 from air inlet 31 circulates upwardly in thedirection of arrow A₃ thereby extending piston 23 within inner cylinder26. Accordingly, cylinder body 24 is a double acting cylinder providingboth compression and extension of piston 23. Air 33 and air 37 arepressurized, for example air 33 and air 37 can be pressurized up toabout 100 psi, and air 33 and 37 is clear of oil and water.

Piston rod 38 extends from piston 23 of cylinder body 24 as shown inFIG. 3A. The size of actuator 22 a–22 d in the extended position ofpiston rod 38 is inversely proportional to the minimum size of a virtualobject that can be grasped by a user of system 10. The size of actuator22 a–22 d can be defined by the compression rate which corresponds tothe rate of closing of a respective digit 13–16.

Preferably, for the “large” size, cylinder body 24 a has a length ofabout 1.65 inches in compressed position and a length of about 3.0inches in the extended position, cylinder body 24 b has a length ofabout 1.75 inches in compressed position and a length of about 3.25inches in the extended position, cylinder body 24 c has a length ofabout 2.0 inches in compressed position and a length of about 3.75inches in the extended position, cylinder body 24 d has a length ofabout 1.90 inches in compressed position and a length of about 3.50inches in the extended position. The size of actuator 22 a–22 d for“medium” size and “small” size are respectively 10% and 20% less thanthe size for the “large” size. Accordingly, cylinder body 24 has acompression rate of 54%, 58% and 62% for the “large”, “medium” and“small” sizes respectively.

Piston rod 38 is fixed within piston 23, as shown in FIG. 3B. Piston 23is received within inner cylinder 26. Preferably, piston 23 is formed ofmaterial having a low coefficient of friction. For example, piston 23can be formed of a carbon and graphite material. Preferably, piston rod38 is coupled to piston 23 with spherical joint 40 and silicon joint 41,for reducing the constraint caused by any error of alignment betweenpiston rod 38 and inner cylinder 26, thereby reducing air leaks betweenpiston 23 and inner cylinder 26.

FIGS. 4A and 4D illustrate attachment of actuator 22 a–22 d to palm base50. Joint 42 rotatably attaches bottom cylinder cap 27 to palm base 50for allowing two degrees of freedom rotation. Joint 42 provides rotationon a flexion axis, axis A_(F), thereby providing front to back rotationof respective digits 13–17 in the direction of arrow A₅ in about a 120°angular range, as shown in FIG. 4B. Joint 42 provides rotation on anabduction/adduction axis, axis A_(A), thereby providing side to siderotation of respective digits 13–17 in the direction of arrow A₄ inabout a 60° angular range.

Bearings 43 rotatably mount side surface 46 of leg 44 of bottom cylindercap 27 to palm base 50 for providing rotation on flexion axis A_(F).Bearings 45 rotatably mount bottom surface 48 of leg 44 of bottomcylinder cap 27 to palm base 50 for providing rotation onabduction/adduction axis, A_(A). Preferably bearings 43 and 45 areminiature, for example, bearings 43 and 45 can have an inner diameter ofabout 0.04 inches and an outer diameter of about 0.125 inches forreducing friction. Flexion axis, A_(F), abduction axis, A_(A), andcylinder axis, A_(C), intersect at a single point, P, for providingimproved error during computation of a kinematics model of each fingerfor a sensor located at point P, as described below.

FIGS. 5A–5C illustrate palm base 50. Tubing 52 connects to air inlet 30of each of actuators 22 a–22 d. Preferably, tubing 52 is mounted orintegrally connected to palm base 50 for allowing full range of motionof actuator 22 a–22 d. Tubing 52 is preferably formed of a flexiblematerial. A suitable material for tubing 52 is silicon, rubber orpolyvinylchloride (PVC). A fabric material can be used to surroundtubing 52. Bottom surface 53 of palm base 50 has a rounded shape asshown in FIG. 5C. Preferably, the outer diameter of bottom surface 53 isin the range of about 10 mm to about 20 mm and most preferably is about13 mm. It will be appreciated that additional tubing not shown can beconnected to air inlet 31 and integrated inside palm base 50.

Palm base 50 is attached approximately at middle portion 54 of palm 55adjacent the metacarpal phalanx crease line, as shown in FIGS. 6A–6B.The shape and size of bottom surface 53 of palm base 50 providescomplete flexion of the metacarpal phalanx and is more comfortable in auser's hand than a flat shape. Digit 13 includes bottom joint 56 andfingertip joint 58. Digits 14–17 each include bottom joint 56, middlejoint 57 and fingertip joint 58. In the compressed position shown inFIG. 6A, piston rod 38 is compressed within cylinder body 24 for closingbottom joint 56, middle 57 and fingertip joint 58, thereby providingforce feedback for simulating grasping of an object. In the extendedposition shown in FIG. 6B, piston rod 38 is extended from cylinder body24 for extending bottom joint 56, middle 57 and fingertip joint 58.

Fingertip joint 58 of each of digits 13–17 is attached to a piston rod38 of a respective actuator 22 a–d with fingertip mount 60, as shown inFIGS. 7A and 7B. Fingertip mount base 61 of fingertip mount 60 isattached adjacent to bottom surface 59 of fingertip joint 58. Aplurality of side mounts 62 are attached to fingertip mount base 61.Side mounts 62 have a rounded shape for sliding over fingertip joint 58.For example, side mounts 62 can be formed of flexible beams. A suitablematerial for side mounts 62 is stainless steel covered with siliconrubber. Screws 65 mount side mounts 62 to fingertip mount base 61. Sidemounts 62 are received in self-locking head 66 for coupling fingertipmount 60 to fingertip joint 58. Release latch 67 releases side mounts 62from self-locking head 66 for removal of fingertip mount 60 fromfingertip joint 58.

Legs 68 a and 68 b extend from bottom surface 69 of fingertip mount base61. Axle 70 connects upper portion 71 of piston rod 38 to legs 68 a and68 b. Ends 72 a and 72 b of axle 70 are rotatably mounted to respectivelegs 68 a and 68 b with bearings 74 for providing one degree of freedomrotation. Bearings 74 can be similar to bearings 43 and 45 describedabove.

FIGS. 8–11 illustrate sensing system 80. Sensing system 80 compriseslinear sensor 81, abduction angular sensor 100, flexion angular sensor102 and force sensor 110 which are each coupled to palm base 50 forexample with a PCB sensor board. Linear sensor 81 includes reflectiveinfrared sensors 82 a, 82 b and 82 c which are mounted to palm base 50and coupled to a respective actuator 22 a–22 d, as shown in FIG. 8A.Reflective infrared sensor 82 a, 82 b and 82 c measure the linearposition of digits 13–17.

Fiber optic cables 83 a, 83 b and 83 c connect respective reflectiveinfrared sensors 82 a, 82 b and 82 c to bottom cylinder cap 27. Fiberoptic cables 83 a, 83 b and 83 c extend through respective apertures 84a, 84 b and 84 c in bottom cylinder cap 27. Infrared waves 85 generatedfrom reflective infrared sensor 82 a travel through fiber optic cable 83a and are emitted by infrared emitter 86 coupled to fiber optic cable 83a. Infrared waves 85 are reflected by mirror 87 as reflected infraredwaves 88. Mirror 87 is attached to bottom surface 99 of piston 23.Mirror 87 is thin, preferably having a thickness of about 0.02 inches toabout 0.04 inches. Infrared waves 85 can also be reflected off mirror 27towards inner cylinder 26 and reflected off inner cylinder 26. Reflectedinfrared waves 88 are received at infrared receptors 89 a, 89 b coupledto fiber optic cables 83 b, 83 c. Reflected infrared waves 88 travelthrough fiber optic cables 83 b and 83 c to reflective infrared sensors82 b, 82 c. Reflective infrared sensors 82 b, 82 c use the values ofreflected infrared waves 88 to determine the position of piston 23. Itwill be appreciated that additional infrared emitters and infraredreceptors can be used in accordance with the teachings of the presentinvention to increase accuracy of the linear position measurement.

Preferably, reflective material 90 combined with absorbing material 91form cover 95 of outside portion 34 of inner cylinder 26 to allow innercylinder 26 to reflect infrared waves. Surface 92 of reflective material90 increases progressively from bottom portion 32 to top portion 36 ofinner cylinder 26. Surface 93 of absorbing material 91 decreases frombottom portion 32 to top portion 36 of inner cylinder 26. Thecombination of progressively increasing absorptive material andprogressively decreasing absorptive material reduces sudden intensityvariations between extreme positions at bottom portion 32 and topportion 36 of inner cylinder 26 for allowing accurate calibration ofreflective infrared sensors 82 a, 82 b and 82 c.

Abduction angular sensor 100 measures the abduction angle, angle A_(A)for measuring abduction motion, as shown in FIG. 9A. Abduction anglesensor 100 is mounted to palm base 50. Flexion angle sensor 102 measuresangle flexion, angle A_(F), for measuring flexion motion, as shown inFIG. 9B. Flexion angle sensor 102 is mounted to bottom surface 105 ofbottom cylinder cap 27. A pair of polarized magnet discs 108, 109 aremounted at 90° to one another to provide a magnetic field having amagnetic field of constant variation for abduction angle sensor 100 andflexion angle sensor 102, as shown in FIG. 9C. Legs 106 extend frombottom cylinder cap 27. Magnetic disc 108 is coupled by axle 104 to legs106 of bottom cylinder cap 27 with bearings 107. The axis of magnet disc108 and the axis of magnet disc 109 intersect at one point P₂. Eachpoint around P₂ has a determined intensity of the magnetic field whichis independent of motion of cylinder body 24. Abduction angle sensor 100and flexion angle sensor 102 measure the magnetic field of magneticdiscs 108 and 109. For example, abduction angle sensor 100 and flexionangle sensor 102 can be Hall effect sensors which sense magnetic fields.Abduction angle sensor 100 measures abduction rotation of about 60degrees from about −30 degrees to about 30 degrees. Flexion angle sensor102 measures flexion rotation of about 120 degrees from about 10 degreesto about 110 degrees.

Force sensor 110 measures forces applied by fingertip joint 58, as shownin FIG. 10. Force sensor 110 comprises strain gauge 112 positioned onportion 114 of palm base 50 adjacent to respective rotatably mountedactuators 22 a–22 d. Fingertip forces in the direction of arrows F₁ andF₂ are measured based on the torque value represented by torque T,measured by strain gauge 112, angle θ and distance D.

FIG. 11 is a schematic diagram of actuator interface 200. Positionsignals 201 from sensing system 80 are received at analog demultiplexer202. Position signals 201 from sensing system 80 can include signalsfrom linear sensor 81, abduction angle sensor 100, flexion angle sensor102 and force sensor 110 respectively received from actuator 22 a–22 dof a small hand, a medium hand or a large hand. Analog demultiplexer 202decouples position signals 201 from sensing system 80. Output signals203 from analog demultiplexer 202 are converted by analog to digitalconverter 204 to digital position signals 205. Digital position signals205 are received at on-board computer 206 and forwarded to host computer207. Digital signals 205 can be forwarded, for example, over an RS232connection to host computer 207. For example, on-board computer 206 canbe an embedded Pentium PC.

Host computer 207 determines force feedback to be applied to actuators22 a–22 d. Force feedback signals 208 generated by host computer 207 areforwarded to on-board computer 206. On-board computer 206 passes valvecontrol signals 209 to digital to analog converter 210. Analog valvecontrol signals 211 are received at valve controller 212. Valvecontroller 212 controls intake valves 213 and exhaust valves 215 todetermine a pressure for pressurized air 216. Air pressure is providedby air compressor 217. Pressurized air 215 is sensed by pressure sensors218. Pressure output 219 from pressure sensor 218 is converted withanalog to digital converter 220 and is received at on-board computer206. Multiplexer pneumatic valves 222 interface actuators 22 a–22 d forproviding pressurized air 215. Multiplexer pneumatic valves 222 arecontrolled by on-board computer 206 through I/O port 224. Actuatorinterface 200 is similar to the interface described in U.S. Pat. No.5,354,162 hereby incorporated by reference into this application.

Monitor 225 can display a virtual environment simulation, interactingwith host computer 207. If complexity of on-board computer 206 isincreased host computer 207 can be omitted.

Kinematic transformations are used to transform the desired position ofactuators 22 a–22 d into a position of piston 23 for extending pistonrod 38 from outer cylinder 25, as shown in FIGS. 6A and 6B. For example,conventional techniques for inverse kinematic transformations to outputthe lengths of cylinders or pistons necessary to reach a desiredposition, such as described in J. E. Dieudone, R. V. Parrish, & R. E.Bardusch, An Actuators Extension Transformation for a Motion Simulatorand an Inverse Transformation Applying Newton-Raphson's Method, NASA,1972 hereby incorporated by reference into this application and forforward kinematics transformations such as described in C. C. Nguyen &F. J. Pooran, Kinematic Analysis and Workspace Determination of a 6 DOFCKCM Robot End-Effector, Journal of mechanical Working Technology, 1989,00. 283–294, hereby incorporated by reference into this application, canbe implemented by host computer 207.

It is to be understood that the above-described embodiments areillustrative of only a few of the many possible specific embodimentswhich can represent applications of the principles of the invention.Numerous and varied other arrangements can be readily devised inaccordance with these principles by those skilled in the art withoutdeparting from the spirit and scope of the invention.

1. A force feedback and sensing system for placement in a handcomprising: one or more actuator systems each connectable to arespective digit of said hand; said actuator system comprising a pistonmoveable within a double acting cylinder, said double acting cylindercomprises: an inner cylinder; an outer cylinder; said inner cylinder andsaid outer cylinder being seated on a bottom cylinder cap; a first inletformed in a bottom portion of said outer cylinder; and a second inletformed in said bottom cylinder cap and in communication with said innercylinder, a palm base positioned on a palm of said hand, said actuatorsystem being rotatably mounted to said palm base for providing twodegrees of freedom or rotation of said actuator system; and one or moresensing systems each connectable to a respective one of said actuatorsystems, wherein air circulated upwardly from said first inlet betweenan inside surface of said outer cylinder and an outside surface of saidinner cylinder an downwardly within said inner cylinder for compressingsaid piston and air circulated from said second inlet upwardly forextending said piston.
 2. The system of claim 1 wherein said innercylinder is formed of glass.
 3. The system of claim 1 wherein said outercylinder is formed of metal.
 4. The system of claim 1 furthercomprising: a first gasket positioned between a bottom portion of saidinner cylinder and said outer cylinder adjacent said bottom cylindercap, said first gasket having an aperture in communication with saidfirst inlet.
 5. The system of claim 1 further comprising a second gasketpositioned between a top portion of said inner cylinder and said outercylinder, said second gasket having an aperture for receiving said aircirculating upwardly from said first inlet between said inside surfaceof said outer cylinder and said outside surface of said inner cylinder.6. The system of claim 1 further comprising: a piston rod coupled tosaid piston with a spherical joint.
 7. The system of claim 6 furthercomprising: a shaft guide positioned within a top portion of said innercylinder, said piston rod sliding within said shaft guide.
 8. The systemof claim 7 wherein said shaft guide is formed of a material having a lowcoefficient of friction.
 9. The system of claim 8 wherein said shaftguide is formed of a nylon and molybdeum material.
 10. The system ofclaim 1 wherein said piston is formed of a material having a lowcoefficient of friction.
 11. The system of claim 10 wherein said pistonis formed of a carbon graphite material.
 12. The system of claim 1wherein said actuator system is mounted with a first joint, said firstjoint having a pair of bearings wherein each bearing is mounted to saidactuator system for providing a first of said two degrees of freedom ona flexion axis.
 13. The system of claim 12 wherein said actuator systemis mounted with a second joint, said second joint having a pair ofbearings wherein each being is mounted to said actuator system forproviding a second of said two degrees of freedom in an abduction axis.14. The system of claim 13 wherein said flexion axis and said abductionaxis intersect at a point.
 15. The system of claim 1 further comprising:air tubing connected to said actuator systems, wherein said air tubingis integrally connected to said palm base.
 16. The system of claim 1wherein said palm base has a rounded bottom surface.
 17. The system ofclaim 16 wherein an outer diameter of said bottom surface of said palmbase is in a range of about 10 mm to about 20 mm.
 18. The system ofclaim 1 wherein said actuator system is selected from the groupcomprising a “large” hand having a compression rate of about 54%, a“medium” hand having a compression rate of about 58% and a “small” handhaving a compression rate of about 62%.
 19. The system of claim 1wherein said actuator system includes a piston and a piston rod attachedto said piston and a sensing system comprises a linear sensor formeasuring a distance of said piston rod within said cylinder.
 20. Thesystem of claim 19 wherein said linear sensor comprises: a reflectiveinfrared sensor mounted to said palm base; one or more infrared emittersattached to a bottom of said cylinder; one or more infrared receptorsattached to a bottom of said cylinder; fiber optic cables connectingsaid infrared sensor to said one or more infrared emitters and said oneor more infrared receptors; and a mirror coupled to a bottom surface ofsaid piston, wherein infrared waves generated by said one or moreinfrared emitters are reflected off said mirror as reflected infraredwaves and received at said one or more infrared receptors, saidreflected infrared waves being sent to said reflective infrared sensorsover said fiber optic cables, values of said reflected waves being usedto determine a position of said piston rod.
 21. The system of claim 20wherein said linear sensor comprises two infrared receptors.
 22. Thesystem of claim 1 wherein said sensing system comprises an abductionangle sensor for measuring rotation on an abduction axis and a flexionangle sensor for measuring rotation on a flexion axis.
 23. The system ofclaim 1 wherein said sensing system comprises a force sensor formeasuring forces applied to a fingertip joint of said digit.
 24. Thesystem of claim 1 wherein said palm base is attached to a glove, saidglove being received over said hand.
 25. The system of claim 1 whereinsaid palm base is attached to said hand with a hand mount, said handmount including one or more side mounts attached to a hand mount base,wherein said hand is received between a bottom surface of said palm baseand a top surface of said hand mount base.
 26. The system of claim 25wherein said hand mount includes one or more apertures for receiving anattachment to a wrist position sensor.
 27. A force feedback and sensingsystem for placement in a hand comprising: one or more actuator systemseach connectable to a respective digit of said hand; said actuatorsystem comprising a piston moveable within a double acting cylinder,said actuator system is connected to said respective digit with afingertip mount, said fingertip mount including one or more side mountsattached to a fingertip mount base, said side mounts slide over saiddigit and said fingertip mount base being attached adjacent a bottomsurface of a fingertip joint of said digit a palm base positioned on apalm of said hand, said actuator system being rotatable mounted to saidpalm base for providing two degrees of freedom of rotation of saidactuator system; and one or more sensing systems each connectable to arespective one of said actuator systems wherein said side mounts areattached with a self-locking head to said fingertip mount base.
 28. Thesystem of claim 27 wherein said actuator system includes a piston and apiston rod attached to said piston, said piston rod being rotatablymounted with a joint to said fingertip mount.
 29. The system of claim 28wherein said joint includes a pair of bearings.
 30. A force feedback andsensing system for placement in a hand comprising: one or more actuatorsystems each connectable to a respective digit of said hand; saidactuator system comprising a piston moveable within a double actingcylinder, a palm base positioned on a palm of said hand, said actuatorsystem being rotatably mounted to said palm base for providing twodegrees of freedom of rotation of said actuator system, said actuatorsystem includes a piston and a piston rod attached to said piston and asensing system comprises a linear sensor for measuring a distance ofsaid piston rod within said cylinder, said linear sensor comprises: areflective infrared sensor mounted to said palm base; one or moreinfrared emitters attached to a bottom of said cylinder; one or moreinfrared receptors attached to a bottom of said cylinder; fiber opticcables connecting said infrared sensor to said one or more infraredemitters and said one or more infrared receptors; and a mirror coupledto a bottom surface of said piston, wherein infrared waves generated bysaid one or more infrared emitters are reflected off said mirror asreflected infrared waves and received at said one or more infraredreceptors, said reflected infrared waves being sent to said reflectiveinfrared sensors over said fiber optic cables, values of said reflectedwaves being used to determine a position of said piston rod and whereinsaid actuator system comprises an inner cylinder within an outercylinder, said infrared emitter and said infrared receptor beingpositioned at said bottom of said inner cylinder, a cover positioned onthe outer portion of said inner cylinder, said cover being formed of areflective material and an absorbing material, a surface of saidreflective material increasing progressively from a bottom portion to atop portion of said inner cylinder and a surface of said absorbingmaterial decreasing progressively from said bottom portion to said topportion of said inner cylinder, wherein said infrared waves generated bysaid one or more infrared emitters are reflected off said mirror andsaid inner cylinder to said one or more infrared receptors.
 31. A forcefeedback and sensing system for placement in a hand comprising: one ormore actuator systems each connectable to a respective digit of saidhand; said actuator system comprising a piston moveable within a doubleacting cylinder, a palm base positioned on a palm of said hand, saidactuator system being rotatably mounted to said palm base for providingtwo degrees of freedom of rotation of said actuator system; and one ormore sensing systems each connectable to a respective one of saidactuator systems said sensing system comprises an abduction angle sensorfor measuring rotation on an abduction axis and a flexion angle sensorfor measuring rotation on a flexion axis wherein said abduction anglesensor is mounted to said palm base and said flexion angle sensorcomprises a pair of polarized magnetic discs forming a magnetic fieldwith a constant variation of intensity, said abduction angle sensor andsaid flexion angle sensor measuring said intensity of said magneticfield.
 32. A force feedback and sensing system for placement in a handcomprising: one or more actuator systems each connectable to arespective digit of said hand; said actuator system comprising a pistonmoveable within a double acting cylinder, a palm base positioned on apalm of said hand, said actuator system being rotatably mounted to saidpalm base for providing two degrees of freedom of rotation of saidactuator system; and said palm base is attached to said hand with a handmount, said hand mount including one or more side mounts attached to ahand mount base, wherein said hand is received between a bottom surfaceof said palm base and a top surface of said hand mount base and whereinsaid side mounts are attached with a self-locking head to said handmount base.
 33. A method for providing force feedback to a handcomprising: providing one or more actuator systems each connectable to arespective digit of said hand; said actuator system comprising a pistonmoveable within a double acting cylinder; said double acting cylindercomprises: an inner cylinder; an outer cylinder; said inner cylinder andsaid outer cylinder being seated on a bottom cylinder cap; a first inletformed in a bottom portion of said outer cylinder; and a second inletformed in said bottom cylinder cap and in communication with said innercylinder; a palm base positioned on a palm of said hand, said actuatorsystem being rotatably mounted to said palm base for providing twodegrees of freedom of rotation of said actuator system; and sensing aposition of said hand with one or more sensing systems each connectableto a respective one of said actuator systems, wherein air circulatesupwardly from said first inlet between an inside surface of said outercylinder and an outside surface of said inner cylinder and downwardlywithin said inner cylinder for compressing said piston and aircirculates from said second inlet upwardly for extending said piston.